The present invention concerns a system for adjusting the alignment of a back cover which screws onto the middle part of a watchcase with respect to a vertical 12 o""clock-6 o""clock axis.
As the back cover of a watchcase is being screwed onto the middle part of the case, it frequently happens that, when the back cover is completely screwed on, one can see that the decorative markings or designs which may have been made for example by die stamping or engraving on the face of the back cover located on the side of the watch wearer""s wrist, are not properly aligned with respect to the vertical 12 o""clock-6 o""clock axis of said watch, which, of course, is detrimental to the aesthetic appearance of said watch.
While this defective appearance may be tolerated for inexpensive watches, it constitutes a very inconvenient drawback for more expensive watches.
In order to overcome this drawback, the only solution known to date consists in coupling a back cover to a determined watchcase during machining, so as to ensure that, once completely screwed on, the back cover is perfectly aligned with the 12 o""clock-6 o""clock axis of the watch. This solution is however unsatisfactory since problems arise if the original back cover of the watch is ever lost or ruined and it becomes necessary to replace it with another back cover, which, one cannot be sure, will still be properly aligned with the vertical 12 o""clock-6 o""clock axis, once it is screwed onto the middle part.
The object of the present invention is to overcome this drawback in addition to others by proposing a system which, after screwing a back cover onto the middle part of a watchcase, enables the alignment of the back cover to be adjusted simply and efficiently with respect to the 12 o""clock-6 o""clock axis of the watch, so as to guarantee the proper disposition of the markings and other decorative designs which have been added to the face of the back cover of the watch oriented towards the side of the watch wearer""s wrist.
The present invention thus concerns a device for securing a back cover to a middle part of a watchcase, the back cover having a screw thread on its outer periphery, the device being characterised in that it includes an intermediate element forcibly driven into the lower part of the middle part of the watch, the back cover being screwed via its screw thread onto the intermediate element which has, for this purpose, on its inner periphery, a complementary screw thread, this intermediate element being capable of being forced to pivot with respect to the middle part of the watch to adjust the alignment of said back cover with respect to the vertical 12 o""clock-6 o""clock axis of said watch.
As a result of these features, the present invention provides a device for securing a watchcase back cover which not only enables the back cover to be completely screwed onto the middle part of the watch so as to assure the sealing thereof and to avoid as far as possible any risk of losing said back cover, then, although the back cover is tightly screwed, enables the back cover to be pivoted with respect to the middle part in order to make up for any lack of alignment of the markings or designs made on the visible face of said back cover with respect to the 12 o""clock-6 o""clock axis of the watch.
The problems of the prior art are thus resolved. In particular, one is no longer obliged to machine the back covers and the middle parts in pairs with great precision in order to ensure that, during assembly, when a back cover is completely screwed onto the corresponding middle part, the back cover will be properly aligned with respect to the vertical axis of the watch. By reducing the requirements as to the precision with which the back covers and middle parts have to be machined, the present invention thus allows the manufacturing costs to be substantially reduced and limits the number of parts which have to be discarded because of machining defects, which, of course, has a favourable impact on the cost price of the finished watch.
According to another feature of the invention, the intermediate element includes a resilient blocking element and a metal element which is arranged concentrically inside of the resilient blocking element, the back cover being screwed onto the metal element so that, when the back cover is completely screwed onto said metal element, the metal element can be forced to pivot with respect to the middle part of the watch, by sliding on the resilient blocking element which remains fixed up to a stop point from which the metal element becomes fixed again with respect to the metal blocking element, which, in turn, can be forced to pivot by sliding on the middle part of the watch by being driven to pivot by said metal element, this allowing the alignment of the back cover to be adjusted with respect to the vertical 12 o""clock-6 o""clock axis of said watch.
According to another feature of the invention, the alignment adjustment torque of the back cover with respect to the vertical axis is less than the blocking torque of the back cover on the intermediate element via which said back cover is mounted on the middle part.
One can thus be sure that the back cover is not liable to become unscrewed when it is pivoted to adjust its vertical alignment.